U.S. patent number 9,712,982 [Application Number 15/252,649] was granted by the patent office on 2017-07-18 for mobile communication system, base station, and user terminal.
This patent grant is currently assigned to KYOCERA Corporation. The grantee listed for this patent is KYOCERA CORPORATION. Invention is credited to Noriyoshi Fukuta, Hiroyuki Urabayashi.
United States Patent |
9,712,982 |
Urabayashi , et al. |
July 18, 2017 |
Mobile communication system, base station, and user terminal
Abstract
A user terminal according to one aspect executes a first and
second DRX operations. The first DRX operation is an operation of
discontinuously monitoring first control information, which is
transmitted from the base station via PDCCH, using a C-RNTI that
uniquely identifies the user terminal in a cell of the base
station. The second DRX operation is an operation of
discontinuously monitoring second control information, which is
transmitted from the base station via the PDCCH, using a group RNTI
assigned to a terminal group including the user terminal. The user
terminal monitors the first control information in a first ON
duration for the first DRX operation, and monitors the second
control information in a second ON duration for the second DRX
operation, the second ON duration being independent of the first ON
duration.
Inventors: |
Urabayashi; Hiroyuki (Yokohama,
JP), Fukuta; Noriyoshi (Inagi, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
KYOCERA CORPORATION |
Kyoto |
N/A |
JP |
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Assignee: |
KYOCERA Corporation (Kyoto,
JP)
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Family
ID: |
54144805 |
Appl.
No.: |
15/252,649 |
Filed: |
August 31, 2016 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20160373901 A1 |
Dec 22, 2016 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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PCT/JP2015/058582 |
Mar 20, 2015 |
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Foreign Application Priority Data
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Mar 20, 2014 [JP] |
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2014-058040 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W
72/1289 (20130101); H04W 76/40 (20180201); H04W
4/06 (20130101); H04W 76/28 (20180201); H04W
72/005 (20130101); H04W 48/12 (20130101); H04W
72/042 (20130101); H04W 8/26 (20130101); H04W
88/02 (20130101); H04W 88/12 (20130101) |
Current International
Class: |
H04W
4/06 (20090101); H04W 76/04 (20090101); H04W
76/00 (20090101); H04W 72/04 (20090101); H04W
72/00 (20090101); H04W 72/12 (20090101); H04W
48/12 (20090101); H04W 88/02 (20090101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
International Search Report issued in PCT/JP2015/058582; mailed
Jun. 16, 2015. cited by applicant .
Written Opinion issued in PCT/JP2015/058582; mailed Jun. 16, 2015.
cited by applicant .
3rd Generation Partnership Project; Technical Specification Group
Radio Access Network; Evolved Universal Terrestrial Radio Access
(E-UTRA) and Evolved Universal Terrestrial Radio Access Network
(E-UTRAN); Overall description; Stage 2; 3GPP TS 36.300 V12.0.0;
Dec. 2013; pp. 1-208; Release 12; 3GPP Organizational Partners.
cited by applicant .
Huawei, HiSilicon; Group Scheduling--alternative solution for group
communication; 3GPP TSG-RAN WG2 #85; R2-140265; Feb. 10-14, 2014;
pp. 1-4; Prague, Czech Republic. cited by applicant .
CMCC; Discussion on L1 signaling design for TDD eIMTA; 3GPP TSG-RAN
WG1 Meeting #74bis; R1-134568; Oct. 7-11, 2013; pp. 1-4; Guangzhou,
China. cited by applicant .
Alcatel-Lucent, Alcatel-Lucent Shanghai Bell; Further discussions
on DCI overhead reduction for carrier aggregation; 3GPP TSG-RAN WG1
Meeting #66bis; R1-113309; Oct. 10-14, 2011; pp. 1-5; Zhuhai.
China. cited by applicant .
Intel Corporation; Signaling mechanism for TDD UL/DL
reconfiguration; 3GPP TSG-RAN WG1 #74; R1-132926; Aug. 19-23, 2013;
pp. 1-5; Barcelona, Spain. cited by applicant .
Panasonic; Reconfiguration message transmission details; 3GPP
TSG-RAN WG1 Meeting 74; R1-133204; Aug. 19-23, 2013; pp. 1-4;
Barcelona, Spain. cited by applicant .
JP Office Action dated Dec. 6, 2016 from corresponding JP Appl No.
2016-508833, with concise statement of relevance, 7 pp. cited by
applicant.
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Primary Examiner: Jiang; Charles C
Assistant Examiner: Khawar; Saad
Attorney, Agent or Firm: Studebaker & Brackett PC
Claims
The invention claimed is:
1. A user terminal configured to communicate with a base station,
comprising: a controller configured to execute a first
discontinuous reception (DRX) operation and a second DRX operation,
wherein the first DRX operation is an operation of discontinuously
monitoring first control information, which is transmitted from the
base station via a physical downlink control channel (PDCCH), using
a cell-radio network temporary identifier (C-RNTI) that uniquely
identifies the user terminal in a cell of the base station, the
second DRX operation is an operation of discontinuously monitoring
second control information, which is transmitted from the base
station via the PDCCH, using a group RNTI assigned to a terminal
group including the user terminal, wherein the group RNTI is used
to allocate first physical downlink shared channel (PDSCH)
resources for multicast data transmission to the terminal group,
the controller is configured to monitor the first control
information in a first ON duration for the first DRX operation, and
to monitor the second control information in a second ON duration
for the second DRX operation, the second ON duration being
independent of the first ON duration, and in response to receiving
the second control information using the group RNTI, the controller
receives multicast data included in the first PDSCH resources
within a same subframe as the second control information.
2. The user terminal according to claim 1, wherein the second
control information is allocated in a common search space of the
PDCCH.
3. The user terminal according to claim 1, wherein the controller
is further configured to execute a process of receiving third
control information, which is transmitted from the base station via
the PDCCH, using a fixed RNTI that predefined in a system, the
third control information includes information indicating
allocation of second PDSCH resources, the second PDSCH resources
include: a plurality of service identifiers, wherein each service
identifier identifies a multicast service provided by the base
station; and plural pieces of scheduling information corresponding
to the service identifiers on a one-to-one basis, and the
controller is further configured to receive the service identifiers
and the plural pieces of scheduling information, based on the third
control information received using the fixed RNTI.
4. The user terminal according to claim 1, wherein the controller
is further configured to execute a process of receiving, from the
base station, a message including a plurality of service
identifiers and a plurality of group RNTIs, wherein each service
identifier identifies a multicast service provided by the base
station, the group RNTIs correspond to the service identifiers on a
one-to-one basis, and the message is transmitted to a plurality of
user terminals including the user terminal.
5. A device to be equipped in a user terminal configured to
communicate with a base station, comprising: at least one processor
communicatively coupled to a memory, said at least one processor
configured to execute a first discontinuous reception (DRX)
operation and a second DRX operation, wherein the first DRX
operation is an operation of discontinuously monitoring first
control information, which is transmitted from the base station via
a physical downlink control channel (PDCCH), using a cell-radio
network temporary identifier (C-RNTI) that uniquely identifies the
user terminal in a cell of the base station, the second DRX
operation is an operation of discontinuously monitoring second
control information, which is transmitted from the base station via
the PDCCH, using a group RNTI assigned to a terminal group
including the user terminal, wherein the group RNTI is used to
allocate first physical downlink shared channel (PDSCH) resources
for multicast data transmission to the terminal group, the at least
one processor is configured to monitor the first control
information in a first ON duration for the first DRX operation, and
to monitor the second control information in a second ON duration
for the second DRX operation, the second ON duration being
independent of the first ON duration, and in response to receiving
the second control information using the group RNTI, the at least
one processor is configured to receive multicast data included in
the first PDSCH resources within a same subframe as the second
control information.
Description
TECHNICAL FIELD
The present disclosure relates to a mobile communication system
into which a group communication function is introduced.
BACKGROUND ART
In 3rd Generation Partnership Project (3GPP) that is a mobile
communication system standardization project, a Multimedia
Broadcast Multicast Service (MBMS) has been established (see
Non-Patent Literature 1). In the MBMS, a plurality of user
terminals receives an MBMS service that is provided from a network
in a multicast or broadcast manner. For example, the MBMS service
is a broadcast video delivery.
In 3GPP, standardization for newly introducing a group
communication function is scheduled to be conducted in Release 12.
For example, the group communication is a group call (voice over
Internet protocol (VoIP)) based on packet communication. In the
group communication, basically, unicasting is applied to uplink
communication, and unicasting or multicasting is applied to
downlink communication.
CITATION LIST
Non Patent Literature
Non patent Literature 1: 3GPP Technical Specification "TS36.300
V12.0.0," Jan. 10, 2014
SUMMARY
A user terminal according to one aspect is configured to
communicate with a base station. The user terminal includes a
controller configured to execute a first discontinuous reception
(DRX) operation and a second DRX operation. The first DRX operation
is an operation of discontinuously monitoring first control
information, which is transmitted from the base station via a
physical downlink control channel (PDCCH), using a cell-radio
network temporary identifier (C-RNTI) that uniquely identifies the
user terminal in a cell of the base station. The second DRX
operation is an operation of discontinuously monitoring second
control information, which is transmitted from the base station via
the PDCCH, using a group RNTI assigned to a terminal group
including the user terminal. The controller is configured to
monitor the first control information in a first ON duration for
the first DRX operation, and to monitor the second control
information in a second ON duration for the second DRX operation,
the second ON duration being independent of the first ON
duration.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a configuration diagram illustrating an LTE system
according to first to third embodiments.
FIG. 2 is a block diagram illustrating a UE according to the first
to third embodiments.
FIG. 3 is a block diagram illustrating an eNB according to the
first to third embodiments.
FIG. 4 is a protocol stack diagram of a radio interface according
to the first to third embodiments.
FIG. 5 is a diagram illustrating a radio frame according to the
first to third embodiments.
FIGS. 6(a) and 6(b) are diagrams for describing an operation
according to the first embodiment.
FIG. 7 is a sequence diagram illustrating an operation when an eNB
allocates a GC-RNTI according to the first embodiment.
FIG. 8 is a sequence diagram illustrating an operation when an EPC
allocates a GC-RNTI according to the first embodiment.
FIG. 9 is a sequence diagram illustrating a group communication
operation according to the first embodiment.
FIGS. 10(a) and 10(b) are diagrams illustrating a first operation
pattern according to a first modified example of the first
embodiment.
FIGS. 11(a) and 11(b) are diagrams illustrating a second operation
pattern according to a first modified example of the first
embodiment.
FIGS. 12(a) to 12(c) are timing charts illustrating an operation
according to a second modified example of the first embodiment.
FIGS. 13(a) and 13(b) are diagrams for describing an operation
according to the second embodiment.
FIGS. 14(a) and 14(b) are diagrams for describing an operation
according to the third embodiment.
DESCRIPTION OF EMBODIMENTS
[Overview of Embodiments]
A user terminal according to an embodiment is configured to
communicate with a base station. The user terminal includes a
controller configured to execute a first discontinuous reception
(DRX) operation and a second DRX operation. The first DRX operation
is an operation of discontinuously monitoring first control
information, which is transmitted from the base station via a
physical downlink control channel (PDCCH), using a cell-radio
network temporary identifier (C-RNTI) that uniquely identifies the
user terminal in a cell of the base station. The second DRX
operation is an operation of discontinuously monitoring second
control information, which is transmitted from the base station via
the PDCCH, using a group RNTI assigned to a terminal group
including the user terminal. The controller is configured to
monitor the first control information in a first ON duration for
the first DRX operation, and to monitor the second control
information in a second ON duration for the second DRX operation,
the second ON duration being independent of the first ON
duration.
In an embodiment, the second control information is allocated in a
common search space of the PDCCH.
In an embodiment, the controller is further configured to execute a
process of receiving third control information, which is
transmitted from the base station via the PDCCH, using a fixed RNTI
that predefined in a system.
In an embodiment, the third control information includes
information indicating allocation of physical downlink shared
channel (PDSCH) resources. A plurality of service identifiers and
plural pieces of scheduling information are allocated in the PDSCH
resources, the plural pieces of scheduling information
corresponding to the service identifiers on a one-to-one basis.
In an embodiment, the controller is further configured to receive
the service identifiers and the plural pieces of scheduling
information, based on the third control information received using
the fixed RNTI.
In an embodiment, the controller is further configured to execute a
process of receiving, from the base station, a message including a
plurality of service identifiers and a plurality of group RNTIs,
the group RNTIs corresponding to the service identifiers on a
one-to-one basis. The message is transmitted to a plurality of user
terminals including the user terminal.
In an embodiment, a device to be equipped in a user terminal
configured to communicate with a base station, includes at least
one processor configured to execute a first discontinuous reception
(DRX) operation and a second DRX operation. The first DRX operation
is an operation of discontinuously monitoring first control
information, which is transmitted from the base station via a
physical downlink control channel (PDCCH), using a cell-radio
network temporary identifier (C-RNTI) that uniquely identifies the
user terminal in a cell of the base station. The second DRX
operation is an operation of discontinuously monitoring second
control information, which is transmitted from the base station via
the PDCCH, using a group RNTI assigned to a terminal group
including the user terminal. The at least one processor is
configured to monitor the first control information in a first ON
duration for the first DRX operation, and to monitor the second
control information in a second ON duration for the second DRX
operation, the second ON duration being independent of the first ON
duration.
In an embodiment, a user terminal includes a controller configured
to execute a process of receiving control information, which is
transmitted from a base station via a PDCCH, using a fixed RNTI
that predefined in a system. The control information includes
information indicating allocation of physical downlink shared
channel (PDSCH) resources. A plurality of service identifiers and
plural pieces of scheduling information are allocated in the PDSCH
resources, the plural pieces of scheduling information
corresponding to the service identifiers on a one-to-one basis. The
controller is further configured to receive the service identifiers
and the plural pieces of scheduling information, based on the
control information received using the fixed RNTI.
In an embodiment, a device to be equipped in a user terminal,
includes at least one processor configured to execute a process of
receiving control information, which is transmitted from a base
station via a PDCCH, using a fixed RNTI that predefined in a
system. The control information includes information indicating
allocation of physical downlink shared channel (PDSCH) resources. A
plurality of service identifiers and plural pieces of scheduling
information are allocated in the PDSCH resources, the plural pieces
of scheduling information corresponding to the service identifiers
on a one-to-one basis. The at least one processor is further
configured to receive the service identifiers and the plural pieces
of scheduling information, based on the control information
received using the fixed RNTI.
In an embodiment, a base station includes a controller configured
to execute a process of transmitting control information, which is
transmitted to user terminals via a PDCCH, using a fixed RNTI that
predefined in a system. The control information includes
information indicating allocation of physical downlink shared
channel (PDSCH) resources. The controller allocates a plurality of
service identifiers and plural pieces of scheduling information
into the PDSCH resources, the plural pieces of scheduling
information corresponding to the service identifiers on a
one-to-one basis.
In an embodiment, a device to be equipped in a base station
includes at least one processor configured to execute a process of
transmitting control information, which is transmitted to user
terminals via a PDCCH, using a fixed RNTI that predefined in a
system. The control information includes information indicating
allocation of physical downlink shared channel (PDSCH) resources.
The at least one processor allocates a plurality of service
identifiers and plural pieces of scheduling information into the
PDSCH resources, the plural pieces of scheduling information
corresponding to the service identifiers on a one-to-one basis.
[First Embodiment]
Hereinafter, exemplary embodiments when the present disclosure is
applied to an LTE system that is a mobile communication system
based on the 3GPP standard will be described.
(1) System Configuration
A system configuration of an LTE system according to the first
embodiment will be described below. FIG. 1 is a configuration
diagram illustrating the LTE system according to the first
embodiment.
The LTE system according to the first embodiment includes user
equipments (UEs) 100, an evolved-UMTS terrestrial radio access
network (E-UTRAN) 10, and an evolved packet core (EPC) 20 as
illustrated in FIG. 1.
The UE 100 corresponds to a user terminal The UE 100 is a mobile
communication apparatus, and performs radio communication with a
cell (a serving cell). A configuration of the UE 100 will be
described later.
The E-UTRAN 10 corresponds to a radio access network. The E-UTRAN
10 includes evolved Node-Bs (eNBs) 200. The eNB 200 corresponds to
a base station. The eNBs 200 are connected to one another via an X2
interface. A configuration of the eNB 200 will be described
later.
The eNB 200 manages one or more cells, and performs radio
communication with the UE 100 that has established a connection
with its own cell. The eNB 200 has a radio resource management
(RRM) function, a user data routing function, a measurement control
function for mobility control/scheduling, and the like. A "cell" is
used as not only a term indicating a minimum unit of a radio
communication area but also a term indicating a function of
performing radio communication with the UE 100.
The EPC 20 corresponds to a core network. The EPC 20 includes a
mobility management entity (MME)/serving-gateway (S-GW) 300. The
MME performs various kinds of mobility controls on the UE 100. The
SGW performs user data transfer control. The MME/S-GW 300 is
connected with the eNB 200 via an S1 interface. The E-UTRAN 10 and
the EPC 20 constitute a network of the LTE system.
FIG. 2 is a block diagram illustrating the UE 100. The UE 100
includes a plurality of antennas 101, a radio transceiver 110, a
user interface 120, a global navigation satellite system (GNSS)
receiver 130, a battery 140, a memory 150, and a processor 160 as
illustrated in FIG. 2. The memory 150 and the processor 160
constitute a controller. The UE 100 may not include the GNSS
receiver 130. The memory 150 may be integrated with the processor
160, and this set (that is, a chip set) may be used as the
processor 160'.
The antennas 101 and the radio transceiver 110 are used for
transmission and reception of radio signals. The radio transceiver
110 converts a baseband signal (a transmission signal) output from
the processor 160 into a radio signal and transmits the radio
signal through the antennas 101. The radio transceiver 110 converts
a radio signal received through the antennas 101 into a baseband
signal (a reception signal) and outputs the baseband signal to the
processor 160.
The user interface 120 is an interface with the user who carries
the UE 100, and includes, for example, a display, a microphone, a
speaker, various kinds of buttons, and the like. The user interface
120 receives an operation from the user, and outputs a signal
indicating content of the operation to the processor 160. In order
to obtain position information indicating a geographical position
of the UE 100, the GNSS receiver 130 receives a GNSS signal and
outputs the received signal to the processor 160. The battery 140
accumulates electric power to be supplied to the respective blocks
of the UE 100.
The memory 150 stores a program executed by the processor 160 and
information used for a process performed by the processor 160. The
processor 160 includes a baseband processor that perform, for
example, modulation, demodulation, encoding, and decoding of the
baseband signal and a central processing unit (CPU) that performs
various kinds of processes by executing the program stored in the
memory 150. The processor 160 may include a codec that encodes and
decodes audio and video signals. The processor 160 executes various
kinds of processes which will be described later and various kinds
of communication protocols.
FIG. 3 is a block diagram illustrating the eNB 200. The eNB 200
includes a plurality of antennas 201, a radio transceiver 210, a
network interface 220, a memory 230, and a processor 240 as
illustrated in FIG. 3. The memory 230 and the processor 240
constitute a controller. The memory 230 may be integrated with the
processor 240, and this set (that is, a chip set) may be used as a
processor.
The antenna 201 and the radio transceiver 210 are used for
transmission and reception of radio signals. The radio transceiver
210 converts a baseband signal (a transmission signal) output from
the processor 240 into a radio signal and transmits the radio
signal through the antenna 201. The radio transceiver 210 converts
a radio signal received by the antenna 201 into a baseband signal
(a reception signal), and outputs the baseband signal to the
processor 240.
The network interface 220 is connected with a neighboring eNB 200
via the X2 interface and connected with the MME/S-GW 300 via the S1
interface. The network interface 220 is used for communication
performed on the X2 interface and communication performed on the S1
interface.
The memory 230 stores a program executed by the processor 240 and
information used for a process performed by the processor 240. The
processor 240 includes a baseband processor that perform, for
example, modulation, demodulation, encoding, and decoding of the
baseband signal and a CPU that performs various kinds of processes
by executing the program stored in the memory 230. The processor
240 executes various kinds of processes which will be described
later and various kinds of communication protocols.
FIG. 4 is a protocol stack diagram of a radio interface in the LTE
system. A radio interface protocol is classified into first to
third layers of an OSI reference model, and the first layer is a
physical (PHY) layer as illustrated in FIG. 4. The second layer
includes a medium access control (MAC) layer, a radio link control
(RLC) layer, and a packet data convergence protocol (PDCP) layer.
The third layer includes a radio resource control (RRC) layer.
The PHY layer performs encoding/decoding, modulation/demodulation,
antenna mapping/demapping, and resource mapping/demapping. User
data and control information are transmitted through a physical
channel between the PHY layer of the UE 100 and the PHY layer of
the eNB 200.
The MAC layer performs preferential control of data, a
retransmission process by hybrid ARQ (HARQ), a random access
sequence, and the like. User data and control information are
transmitted through a transport channel between the MAC layer of
the UE 100 and the MAC layer of the eNB 200. The MAC layer of the
eNB 200 includes a scheduler for deciding transport formats (a
transport block size and a modulation and coding scheme (MCS)) of
an uplink and a downlink and a resource block to be allocated to
the UE 100.
The RLC layer transmits data to an RLC layer of a reception side
using the functions of the MAC layer and the PHY layer. User data
and control information are transmitted through a logical channel
between the RLC layer of the UE 100 and the RLC layer of the eNB
200.
The PDCP layer performs header compression/decompression and
encryption/decryption.
The RRC layer is defined only in a control plane in which control
information is dealt with. Control information (an RRC message) for
various kinds of settings is transmitted between the RRC layer of
the UE 100 and the RRC layer of the eNB 200. The RRC layer controls
the logical channel, the transport channel, and the physical
channel in response to establishment, re-establishment, and release
of the radio bearer. When there is a connection (an RRC connection)
between the RRC of the UE 100 and the RRC of the eNB 200, the UE
100 is in an RRC connected state, and otherwise, the UE 100 is in
an RRC idle state.
A non-access stratum (NAS) layer positioned above the RRC layer
performs session management, mobility management, and the like.
FIG. 5 is a diagram illustrating a radio frame used in the LTE
system. In the LTE system, Orthogonal Frequency Division
Multiplexing Access (OFDMA) is applied for downlink, and Single
Carrier Frequency Division Multiple Access (SC-FDMA) is applied for
uplink.
A radio frame is configured with 10 subframes arranged in a time
direction as illustrated in FIG. 5. Each subframe is configured
with two slots arranged in the time direction. A length of each
subframe is 1 ms, and a length of each slot is 0.5 ms. Each
subframe includes a plurality of resource blocks (RBs) in a
frequency direction and includes a plurality of symbols in the time
direction. Each resource block includes a plurality of sub carriers
in the frequency direction. One resource element (RE) is configured
with one symbol and one sub carrier. Among radio resources (time
and frequency resources) allocated to the UE 100, the frequency
resources can be specified by resource blocks, and the time
resources can be specified by subframes (or slots).
In the downlink, an interval of several symbols at the head of each
subframe is a control region used as a physical downlink control
channel (PDCCH) for transmitting control information mainly. The
remaining interval of each subframe is a data region that can be
used as a physical downlink shared channel (PDSCH) for transmitting
user data mainly.
The eNB 200 transmits information (L1/L2 control information) for
notifying of downlink and uplink resource allocation results to the
UE 100 through the PDCCH. Each PDCCH occupies resources configured
with one or more control channel elements (CCEs). One CCE is
configured with a plurality of REs. One of 1, 2, 4, and 8 is set as
the number of CCEs occupied by the PDCCH (an aggregation
level).
The eNB 200 transmits a plurality of pieces of control information.
The eNB 200 includes CRC bit scrambled using an identifier (Radio
Network Temporary ID (RNTI)) of the UE 100 of a transmission
destination in control information in order to identify the UE 100
of the transmission destination of each control information.
For a plurality of pieces of control information that may be
directed to its own UE, each of the UEs 100 performs descrambling
on the CRC bits using the RNTI of its own UE, performs blind
decoding on the PDCCH, and detects the control information directed
to its own UE.
In order to reduce the number of blind decodings, a CCE serving as
a blind decoding target is limited. A CCE region serving as the
blind decoding target is referred to as "search space." The search
space will be described later in detail.
(2) Operation According to First Embodiment
The LTE system according to the first embodiment supports group
communication. An operation for appropriately controlling the group
communication according to the first embodiment will be described
below.
(2.1) Operation Overview
FIGS. 6(a) and 6(b) are diagrams for describing an operation
according to the first embodiment. FIG. 6(a) illustrates a downlink
subframe according to the first embodiment, and FIG. 6(b)
illustrates an operation environment according to the first
embodiment.
As illustrated in FIGS. 6(a) and 6(b), the LTE system according to
the first embodiment includes an eNB 200 that manages a cell and
transmits control information in a control region (a PDCCH region)
in a downlink subframe and a plurality of UEs 100 that constitute a
terminal group (hereinafter, referred to simply as a "group") that
perform the group communication in the cell. Each group is
identified by a service identifier (hereinafter, referred to as a
"GC service ID"). FIGS. 6(a) and 6(b) illustrate an example in
which UEs 100-1 to 100-3 belong to a group A, and UEs 100-4 to
100-6 belong to a group B.
Each of the UEs 100 is in the RRC connected state, and a different
identifier (cell RNTI (C-RNTI)) is allocated from the eNB 200 to
each UE 100 in the cell.
A group communication identifier (a group communication RNTI
(GC-RNTI)) is allocated to each of the UEs 100 that perform the
group communication. In the first embodiment, a different GC-RNTI
is allocated to each of the UEs 100 for each group. In FIGS. 6(a)
and 6(b), a GC-RNTI(A) is allocated to the UEs 100-1 to 100-3
belonging to the group A, and a GC-RNTI(B) is allocated to the UEs
100-4 to 100-6 belonging to the group B. An operation of allocating
the GC-RNTI will be described later.
The PDCCH region includes a common search space (CSS) in which
control information common to all the UEs 100 in the cell is
arranged and a UE specific search space (USS) in which control
information specific to each of the UEs 100 in the cell is
arranged. The control information common to all the UEs 100 in the
cell is, for example, allocation information related to a broadcast
signal and a paging signal. The control information specific to
each of the UEs 100 in the cell is, for example, allocation
information related to downlink user data. The USS is set according
to the C-RNIT, a subframe number, and the like.
In the first embodiment, the PDCCH region further includes a group
communication search space (GCSS) in which group communication
control information related to the group communication
(hereinafter, referred to as "GC control information") is arranged.
The GC control information is, for example, allocation information
(information of an allocation resource block) related to downlink
user data (group communication data). The GC control information
may include information of the MCS. When semi-persistent scheduling
is performed, information indicating a duration of an allocation
resource block may be included. The GCSS is set according to the
GC-RNTI, the subframe number, and the like. In the first
embodiment, since the GC-RNTI differs according to each group, the
GCSS differs according to each group as well. In FIGS. 6(a) and
6(b), the GCSS corresponding to the group A and the GCSS
corresponding to the group B are individually set.
Hereinafter, a region in which the CSS is set in the PDCCH region
is referred to as a "CSS region," a region in which the USS is set
is referred to as a "USS region," and a region in which the GCSS is
set is referred to as a "GCSS region."
The eNB 200 arranges the GC control information in the GCSS region
according to the GC-RNTI. Specifically, the eNB 200 performs
mapping of the GC control information for the group A in the GCSS
corresponding to the group A, and performs mapping of the GC
control information for the group B in the GCSS corresponding to
the group B. The eNB 200 scrambles the GC control information for
the group A using the GC-RNTI(A) allocated to the group A, and
scrambles the GC control information for the group B using the
GC-RNTI(B) allocated to the group B.
Each of the UEs 100 acquires the GC control information arranged in
the GCSS according to the GC-RNTI allocated to its own UE 100.
Specifically, each of the UEs 100 performs blind decoding
(monitoring) of the GCSS corresponding to the group to which its
own UE 100 belongs using the GC-RNTI allocated to its own UE 100.
Then, each of the UEs 100 acquires the GC control information for
the group to which its own UE 100 belongs through the blind
decoding. For example, the UE 100-1 acquires the GC control
information for the group A through the blind decoding of the GCSS
corresponding to the group A. On the other hand, the UE 100-4
acquires the GC control information for the group B through the
blind decoding of the GCSS corresponding to the group B.
As described above, in the first embodiment, since the GC-RNTI
differs according to each group, the GC control information is
transmitted within the PDCCH region. As a result, for example, a
flexible (dynamic) radio resource allocation can be performed
according to the number of groups, the group communication data
amount, and the like for each group.
(2.2) GC-RNTI Allocation Operation
Next, a GC-RNTI allocation operation according to the first
embodiment will be described.
(2.2.1) First Operation Pattern
In the first operation pattern, the eNB 200 or the core network
(the EPC 20) decides the GC-RNTI according to a request from the UE
100 that attempts to start the group communication. The eNB 200
notifies the UE 100 of the request source of the decided GC-RNTI.
For example, the eNB 200 transmits the GC-RNTI through an
individual RRC message in the unicast manner. In this case, the
GC-RNTI may be included in group communication setting information
(Configuration).
FIG. 7 is a sequence diagram illustrating an operation when the eNB
200 allocates the GC-RNTI.
As illustrated in FIG. 7, in step S11, the UE 100 establishes an
RRC connection with the eNB 200.
Thereafter, the UE 100 performs a group communication initiation
process. In step S12, the UE 100 transmits a GC-RNTI allocation
request (a GC control request) to the eNB 200. The GC control
request includes the GC service ID of the group communication that
the UE 100 desires to join.
In step S13, the eNB 200 that has received the GC control request
derives the GCRNTI from the GC service ID included in the GC
control request. The eNB 200 is assumed to receive a GC service ID
list from the EPC 20 and associate the GC-RNTI with each group
communication. For example, an association timing is a timing at
which the GC service ID list is received from the EPC 20 or a
timing at which the GC control request is received from the UE
100.
In step S14, the eNB 200 transmits a response (a GC control
response) including the GC-RNTI corresponding to the GC service ID
to the UE 100.
The UE 100 acquires and holds the GC-RNTI included in the GC
control response. The UE 100 starts the blind decoding as the
GC-RNTI is held.
FIG. 8 is a sequence diagram illustrating an operation when the EPC
20 allocates the GC-RNTI. When the EPC 20 allocates the GC-RNTI, a
plurality of eNBs 200 can operate in collaboration with one
another. Here, an example in which an MME 300 in the EPC 20
allocates the GC-RNTI is illustrated.
As illustrated in FIG. 8, in step S21, the UE 100 establishes an
RRC connection with the eNB 200.
Thereafter, the UE 100 performs a group communication initiation
process. In step S22, the UE 100 transmits the GC-RNTI allocation
request (the GC control request) to the eNB 200. The GC control
request includes the GC service ID of the group communication that
the UE 100 desires to join.
When the eNB 200 holds an association between the GC service ID and
the GC-RNTI, the eNB 200 may allocates the GC-RNTI based on the
association. Here, the eNB 200 is assumed not to hold the
association. In step S23, the eNB 200 transfers the GC control
request transmitted from the UE 100 to the MME 300.
In step S24, the MME 300 that has received the GC control request
derives the GCRNTI from the GC service ID included in the GC
control request.
In step S25, the MME 300 transmits a response (the GC control
response) including the GC-RNTI corresponding to the GC service ID
to the eNB 200.
In step S26, the eNB 200 that has received the GC control response
transfers the GC control response to the UE 100. Further, when the
GC-RNTI allocated by the MME 300 is identical to an RNTI allocated
by its own eNB 200, the eNB 200 may request the MME 300 to change
the allocation of the GC-RNTI.
The UE 100 acquires and holds the GC-RNTI included in the GC
control response. The UE 100 starts the blind decoding as the
GC-RNTI is held.
(2.2.2) Second Operation Pattern
In the first operation pattern, the eNB 200 notifies the UE 100 of
the GC-RNTI in the unicast manner but may notify of the GC-RNTI in
the broadcast manner.
In the second operation pattern, the eNB 200 transmits a message
including a plurality of GC service IDs that differ according to
each group and a plurality of GC-RNTIs corresponding to the
plurality of GC service IDs within the cell in the broadcast
manner. This message may be a common RRC message (for example, a
system information block).
In the second operation pattern, the UE 100 that has received the
message acquire the GC-RNTI corresponding to the GC service ID of
the group communication that it desires to join from the message
and holds the GC-RNTI. The UE 100 starts the blind decoding as the
GC-RNTI is held.
(2.2.3) Range of GC-RNTI
Table 1 illustrates available RNTIs in the current specification
and ranges of values thereof.
TABLE-US-00001 TABLE 1 Value (hexa-decimal) RNTI 0000 N/A 0001-003C
RA-RNTI, C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary
C-RNTI, TPC-PUCCH-RNTI and TPC-PUSCH-RNTI (see note) 003D-FFF3
C-RNTI, Semi-Persistent Scheduling C-RNTI, Temporary C-RNTI,
TPC-PUCCH-RNTI and TPC-PUSCH-RNTI FFF4-FFFC Reserved for future use
FFFD M-RNTI FFFE P-RNTI FFFF SI-RNTI
As shown in Table 1, an RNTI value has a range of 0000-FFFF. A
"FFF4-FFFC" region reserved for the future use may be used as the
range of the GC-RNTI value. Alternatively, a part of a "0001-003C"
or "003D-FFF3" region may be allocated for the group communication.
Alternatively, when a "0001-003C" or "003D-FFF-3" region is used,
it may be dynamically used, or a part may be cut for the GC-RNTI in
advance.
(2.3) Group Communication Operation
Next, a group communication operation according to the first
embodiment will be described. As described above, the eNB 200
allocates downlink radio resources for the group communication
using, the GC-RNIT.
FIG. 9 is a sequence diagram illustrating a group communication
operation according to the first embodiment. In FIG. 9, the UEs
100-1 to 100-3 are assumed to belong to the same group (the group
A), and the GC-RNIT is assumed to have been allocated. The eNB 200
starts to allocate the downlink radio resources for the group
communication according to a group communication delivery request
transmitted from the EPC 20.
As illustrated in FIG. 9, in step S31, the eNB 200 performs mapping
of the GC control information for the group A in the GCSS
corresponding to the group A, and scrambles the GC control
information for the group A using the GC-RNTI allocated to the
group A. As described above, the GC control information is, for
example, the allocation information (the information of the
allocation resource block) related to the group communication data.
The GC control information may include information of the MCS.
In step S32, the eNB 200 transmits the GC control information and
the group communication data. When the dynamic resource allocation
(dynamic scheduling) is performed, the group communication data is
arranged in a resource block in a data region of a downlink
subframe in which the GC control information is arranged. However,
the eNB 200 may perform a semi-persistent resource allocation
(semi-persistent scheduling).
In step S33, each of the UEs 100 acquires the GC control
information arranged in the GCSS corresponding to the group A
according to the GC-RNTI allocated to its own UE 100. Specifically,
each of the UEs 100 performs the blind decoding (monitoring) of the
GCSS corresponding to the group to which its own UE 100 belongs
using the GC-RNTI allocated to its own UE 100. Each of the UEs 100
acquires the GC control information for the group to which its own
UE 100 belongs through the blind decoding.
In step S34, each of the UEs 100 receives the group communication
data based on the acquired GC control information. Specifically,
each of the UEs 100 demodulates and decodes the group communication
data arranged in the resource block indicated by the GC control
information.
(3) Conclusion of First Embodiment
In the first embodiment, the eNB 200 arranges the GC control
information in the GCSS region according to the GC-RNTI. Each of
the UEs 100 acquires the GC control information arranged in the
GCSS according to the GC-RNTI allocated to its own UE 100. As a
result, the dynamic scheduling in the group communication can be
implemented.
Further, it is possible to collectively allocate the resource
blocks to a plurality of UEs 100 belonging to one group and
collectively transmit (that is, multicast) the group communication
data to a plurality of UEs 100 through the resource blocks. Thus,
the radio resources can be efficiently used.
[First Modified Example of First Embodiment]
The first embodiment has been described in connection with the
example in which the GC-RNTI differs according to each group. In
this case, it is necessary to secure a plurality of GC-RNTIs and a
plurality of GCSSs, and resources are likely to be tight. Thus, one
GC-RNTI may be shared by the respective groups instead of causing
the GC-RNTI to differ according to each group.
In the first modified example of the first embodiment, the GC-RNTI
is a fixed value that is specified on a system in advance. Thus,
the GC-RNTI is common to all groups. In this case, the GC control
information includes information for receiving radio resources
included in the data region other than the PDCCH region in the
downlink subframe. This information includes the information of the
allocation resource block, the information of the MCS, and the
like. When the semi-persistent scheduling is performed, information
indicating the duration of the allocation resource block may be
further included.
In the first modified example of the first embodiment, the user
data or the control information is arranged in the radio resources
indicated by the GC control information together with the GC
service ID. In other words, the GC control information is common to
the respective groups and cut for each group based on the GC
service ID in the data region.
FIGS. 10(a) and 10(b) are diagrams illustrating a first operation
pattern according to the first modified example of the first
embodiment. In the first operation pattern, the user data is
arranged in the radio resources indicated by the GC control
information together with the GC service ID.
As illustrated in FIGS. 10(a) and 10(b), the eNB 200 arranges the
GC control information in the GCSS region according to the GC-RNTI.
The GC-RNTI is common to the groups A and B, and thus the GCSS is
also common to the groups A and B. The eNB 200 scrambles the GC
control information using the GC-RNTI.
The eNB 200 allocates the radio resources in the data region to the
UEs 100 belonging to the groups A and B. In the first operation
pattern, the eNB 200 arranges the GC service ID of the group A, the
GC service ID of the group B, the group communication data of the
group A, and the group communication data of the group B in the
radio resources. Here, the group communication data of the group A
is associated with the GC service ID of the group A. The group
communication data of the group B is associated with the GC service
ID of the group B. For example, a corresponding GC service ID is
added to the head of the group communication data.
The UE 100 acquires the GC control information in the GCSS using
the GC-RNIT allocated to its own UE 100. The UE 100 specifies
allocation radio resources in the data region based on the GC
control information, acquires the GC service ID included in the
specified radio resources, and detects the GC service ID
corresponding to the group communication in which its own UE 100 is
taking part. Then, the UE 100 acquires the group communication data
associated with the detected GC service ID.
FIGS. 11(a) and 11(b) are diagrams illustrating a second operation
pattern according to the first modified example of the first
embodiment. In the second operation pattern, the control
information is arranged in the radio resources indicated by the GC
control information together with the GC service ID.
As illustrated in FIGS. 11(a) and 11(b), the eNB 200 arranges the
GC control information in the GCSS region according to the GC-RNTI.
The GC-RNTI is common to the groups A and B, and thus the GCSS is
also common to the groups A and B. The eNB 200 scrambles the GC
control information using the GC-RNTI.
In the second operation pattern, the eNB 200 allocates radio
resources in which the control information is arranged, radio
resources in which the group communication data of the group A is
arranged, and radio resources in which the group communication data
of the group B is arranged in the data region.
The eNB 200 arranges control information (A) including the GC
service ID of the group A and control information (B) including the
GC service ID of the group B in the radio resources in which the
control information is arranged. The control information (A) is
scheduling information related to the radio resources in which the
group communication data of the group A is arranged. The control
information (B) is scheduling information related to the radio
resources in which the group communication data of the group B is
arranged. The control information (A) and (B) may include the
information of the MCS. Further, when the semi-persistent
scheduling is performed, the control information (A) and (B) may
further include information the duration of the allocation resource
block.
The UE 100 acquires the GC control information in the GCSS using
the GC-RNIT allocated to its own UE 100. The UE 100 specifies the
radio resources in the data region based on the GC control
information, and acquires the control information included in the
specified radio resources. Here, the UE 100 detects the control
information including the GC service ID corresponding to the group
communication in which its own UE 100 is taking part. Then, the UE
100 specifies the radio resources indicated by the detected control
information, and acquires the group communication data included in
the specified radio resources.
[Second Modified Example of First Embodiment]
In the second modified example of the first embodiment, an example
in which the UE 100 that performs the group communication performs
a discontinuous reception (DRX) operation is assumed. The UE 100
that performs the DRX operation monitors control information in a
first ON period in which control information different from the GC
control information is received, and monitors the GC control
information in a second ON period in which the GC control
information is received.
FIGS. 12(a) to 12(c) are timing charts illustrating an operation
according to the second modified example of the first
embodiment.
As illustrated in FIG. 12(a), the UE 100 that performs the DRX
operation monitors the control information different from the GC
control information such as the control information transmitted
using the C-RNTI in an ON period of a DRX cycle. Specifically, the
receiver (the radio transceiver 110) is turned at intervals of the
DRX cycles, and the blind decoding of the PDCCH region is performed
using the C-RNTI.
Here, when the group communication is allocated discontinuously
(periodically), the UE 100 needs to turn on the receiver in the ON
period in which the GC control information is received as well as
the ON period illustrated in FIG. 12(a) as illustrated in FIG.
12(b). Thus, as illustrated in FIG. 12(c), the UE 100 performs
control the receiver is turned on in the ON period illustrated in
FIG. 12(a) and the ON period illustrated in FIG. 12(b).
[Second Embodiment]
A second embodiment will be described focusing on a difference with
the first embodiment. A system configuration according to the
second embodiment is the same as in the first embodiment.
In the first embodiment, the GC control information is arranged in
the GCSS region. On the other hand, in the second embodiment, the
GC control information is arranged in the CSS region without
disposing the GCSS region.
FIGS. 13(a) and 13(b) are diagrams for describing an operation
according to the second embodiment.
As illustrated in FIGS. 13(a) and 13(b), the eNB 200 arranges the
GC control information related to the group communication in the
CSS according to the GC-RNTI allocated to each group. Here, the eNB
200 scrambles the GC control information using the GC-RNTI.
Specifically, the eNB 200 performs mapping of the GC control
information for the group A in the CSS corresponding to the group
A, and performs mapping of the GC control information for the group
B in the CSS corresponding to the group B. The eNB 200 scrambles
the GC control information for the group A using the GC-RNTI(A)
allocated to the group A, and scrambles the GC control information
for the group B using the GC-RNTI(B) allocated to the group B.
The eNB 200 also arranges the control information common to all the
UEs 100 in the cell in the CSS. The eNB 200 scrambles the common
control information, for example, using an SI-RNTI and/or a
P-RNTI.
Each of the UEs 100 acquires the GC control information arranged in
the CSS according to the GC-RNTI allocated to its own UE 100.
Specifically, each of the UEs 100 performs the blind decoding
(monitoring) of the GCSS corresponding to the group to which its
own UE 100 belongs using the GC-RNTI allocated to its own UE 100.
Then, each of the UEs 100 acquires the GC control information for
the group to which its own UE 100 belongs through the blind
decoding.
The remaining points are similar to those in the first embodiment.
Specifically, in the second embodiment, the GC-RNTI differs
according to each group in which the group communication is
performed in the cell.
The eNB 200 or the core network decides the GC-RNTI according to
the request of the UE 100 that desires to start the group
communication. The eNB 200 notifies the UE 100 of the request
source of the decided GC-RNTI.
Alternatively, the eNB 200 transmits a message including a
plurality of GC service IDs that differ according to each group and
a plurality of GC-RNTIs corresponding to the plurality of GC
service IDs within the cell in the broadcast manner.
[Modified Example of Second Embodiment]
The second embodiment has been described in connection with the
example in which the GC-RNTI differs according to each group.
However, similarly to the first modified example of the first
embodiment, one GC-RNTI may be shared by the respective groups.
[Third Embodiment]
A third embodiment will be described focusing on a difference with
the first embodiment. A system configuration according to the
second embodiment is the same as in the first embodiment.
In the first embodiment, the GC control information is arranged in
the GCSS region. On the other hand, in the third embodiment, the GC
control information is arranged in the USS region without disposing
the GCSS region.
FIGS. 14(a) and 14(b) are diagrams for describing an operation
according to the third embodiment.
As illustrated in FIGS. 14(a) and 14(b), the eNB 200 arranges the
GC control information related to the group communication in the
USS according to the GC-RNTI allocated to each group. Here, the eNB
200 scrambles the GC control information using the GC-RNTI.
Specifically, the eNB 200 performs mapping of the GC control
information for the group A in the USS corresponding to the group
A, and performs mapping of the GC control information for the group
B in the USS corresponding to the group B. The eNB 200 scrambles
the GC control information for the group A using the GC-RNTI(A)
allocated to the group A, and scrambles the GC control information
for the group B using the GC-RNTI(B) allocated to the group B.
Each of the UEs 100 acquires the GC control information arranged in
the USS according to the GC-RNTI allocated to its own UE 100.
Specifically, each of the UEs 100 performs the blind decoding
(monitoring) of the GUSS corresponding to the group to which its
own UE 100 belongs using the GC-RNTI allocated to its own UE 100.
Then, each of the UEs 100 acquires the GC control information for
the group to which its own UE 100 belongs through the blind
decoding.
The remaining points are similar to those in the first embodiment.
Specifically, in the third embodiment, the GC-RNTI differs
according to each group in which the group communication is
performed in the cell.
The eNB 200 or the core network decides the GC-RNTI according to
the request of the UE 100 that desires to start the group
communication. The eNB 200 notifies the UE 100 of the request
source of the decided GC-RNTI.
Alternatively, the eNB 200 transmits a message including a
plurality of GC service IDs that differ according to each group and
a plurality of GC-RNTIs corresponding to the plurality of GC
service IDs within the cell in the broadcast manner.
[First Modified Example of Third Embodiment]
The third embodiment has been described in connection with the
example in which the GC-RNTI differs according to each group.
However, similarly to the first modified example of the first
embodiment, one GC-RNTI may be shared by the respective groups.
[Second Modified Example of Third Embodiment]
In the third embodiment, similarly to the second modified example
of the first embodiment, the UE 100 that performs the DRX operation
monitors control information in the first ON period in which
control information different from the GC control information is
received, and monitors the GC control information in the second ON
period in which the GC control information is received.
[Other Embodiments]
The above embodiments have been described in connection with the
example in which each of the UEs 100 belongs to one group, but one
UE 100 may belong to a plurality of groups. In this case, one UE
100 may hold a plurality of GC-RNTIs.
In the above embodiments, the LTE system has been described as an
example of the mobile communication system, but the present
disclosure is not limited to the LTE system and may be applied to
any other system than the LTE system.
The entire contents of Japanese Priority Patent Application No.
2014-058040 (Mar. 20, 2014) are incorporated herein by
reference.
* * * * *